Luke McGrath faces an anxious wait to determine the extent of the knee injury that he picked up in Leinster's win over Toulouse on Saturday.
The scrum-half will undergo scans today, but there were initial fears that he may have suffered a significant injury.
Leo Cullen is hoping that is not the case ahead of the trip to Wasps this weekend, while Joe Schmidt will also be monitoring the situation closely as the Ireland head coach deals with something of an injury crisis at scrum-half ahead of Wednesday's Six Nations squad announcement.
As of today, Conor Murray is the only fit and available regular Irish scrum-half.
Kieran Marmion (ankle) is expected to be included in the squad, but the Connacht man hasn't played since Ireland's win over the All Blacks in November.
While McGrath had to be helped off the pitch shortly after the hour mark, up in Belfast John Cooney was a late withdrawal ahead of Ulster's victory over Racing 92.
Cooney is struggling with a back problem and, like McGrath, is waiting to see how serious it is.
McGrath missed last year's Six Nations due to a knee injury and Leo Cullen is hoping he has not suffered a similarly serious setback.
"Lukey has done something to his knee, we'll get that assessed," the Leinster head coach said.
"It would be a cruel blow for him, but we'll see how it unfolds. I'm only speculating at his stage.
"We'll get him scanned at the start of the week and make a plan from there.
"It was the same last year as well. He picked up a medial injury to his knee, I think it was around this time, off the top of my head. So he missed a few weeks with that.
"It was during that period where Jamison (Gibson-Park) stepped in, and he's been going really well for us as well. We've a few options there."
Leinster will issue a further update on McGrath's condition tomorrow, while Ulster are also expected to offer clarity on Cooney's back injury ahead of Wednesday's Six Nations squad announcement.
Garry Ringrose suffered a 'stinger' late on, but confirmed afterwards that it was nothing serious.